This invention relates generally to an assembly and method for producing a maximum net outward deflection of a forward or aft dome portion of a rocket motor during a solid propellant curing operation and for reducing such deflection in stages at different times during the curing process.
It has long been known that when a propellant is cured under high pressure in a solid propellant rocket motor, the propellant containing motor casing tends to expand in a non-uniform manner. Similarly, when the pressure is reduced in the casing during the curing process, the casing tends to contract in a non-uniform manner. Moreover, as the propellant cures, it tends to shrink inwardly, sometimes resulting in high localized stress fields in the propellant grain at the boundary of the grain/case bond. High localized stress fields and disruptions of the bond between the propellant grain and motor casing have been particularly pronounced in the region of the forward and aft domes. The problem has been recognized as significant in high pressure cured solid propellant motors having both relatively rigid steel casings as well as those having flexible, filament wound casings such as the Boeing SRM-1 and SRM-2 large and small inertial upper stage motors used in the shuttle orbitor program.
By means of my invention, the deleterious effects of this problem are substantially minimized if not altogether eliminated.